Thruster



April 1959 c. c. FAWC-ETT ET AL' 2,880,572 I THRUSTER Filed April 9. 1958 FIG.|.

INVENTOR. CECIL C. FAWCETT CRESTON E LAAGER wzwwpyw w United States Patent THRUSTER Cecil C. Fawcett, Huntingdon Valley, Pa., and (Ireston F. Laager, Beverly, N.J., assignors to the United States of America as represented by the Secretary of the Army Application April 9, 1958, Serial No. 727,510

2 Claims. (Cl. 6019) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to thrusters such as are used to eject a man-seat mass from a moving aircraft, and more particularly to an improved thruster of the type disclosed in a copending application of Albert M. Stott and Herbert A. Magnus, Ser. No. 644,426, filed March 6, 1957, now Patent No. 2,857,889 issued October 28, 1958, for One Stroke Thruster With Speed Reducer.

In the thruster disclosed by the aforesaid application, a cartridge actuated piston operates a second piston through a liquid coupling. A check valve on the second piston allows liquid to flow into a restricted space on the front side of the second piston for cushioning its movement. During movement of this second piston and its rod, the check valve is closed and a high back pressure is developed in the restricted space by limiting the outlet from this space to a small opening having a cross-section which determines to a large extent the speed of the second piston and the force it exerts.

The device of the present invention provides an improved arrangement wherein the function formerly performed by the check valve mentioned above is performed by the piston which is actuated by the gas pressure and functions to drive the liquid into the cylinder from which the thrust is applied to the load. It has been found that this simplifies the construction of the device.

The invention will be better understood from the following description when considered in connection with the accompanying drawings and its scope is indicated by the appended claims.

Referring to the drawings:

Fig. 1 is a sectional view of a preferred embodiment of the invention, and

Fig. 2 is a bottom end view of the device illustrated by Fig. 1.

This device includes a cylinder 10 and a cylinder 11 which are joined together at their adjacent sides, holes 12 being provided in the joining metal to minimize the weight of the device.

The cylinder 10 encloses a piston 13 which is integral with rod 14 and has a longitudinal aperture 15. The rod 14 is adapted to be coupled to the load and is held in its illustrated position by a shear pin 16. Seal rings 17 and 18 surround the rod 14 and the piston 13. The bottom end of the cylinder 10 is enclosed by a plug 19.

The cylinder 11 is closed at its bottom end by a plug 20. Adjacent to this plug is chamber 21 adapted to enclose a receptacle made of very thin pure aluminum and having a filler of silicone oil. At the top end of the cylinder 11 is a firing pin 22 which is held in its illustrated position by a shear pin 23 interposed between it and a collar 24. This collar is fixed in position by a locking 'ice ring 25. The collar 24 and the firing pin 22 are surrounded by seal rings 26 and 27. The firing pin is actuated by gas supplied from an initiator or the like.

Adjacent to the inner end of the collar 24 is a cartridge 28 arranged to be activated by the firing pin 22. Interposed between the cartridge 28 and the chamber 21 is a floating piston 29 which is surrounded by a seal ring 30 and has a skirt 31 perforated as indicated by the numeral 32 and form ng a combustion chamber.

In considering the operation of the device, it is important to understand that (l) a passageway 33 extends from the chamber 21 to the front of the piston 13, (2) a passageway 34, extends from the chamber 21 to the back of the piston 13, (3) the passageway 33 is closed by the skirt 31 as the piston 29 nears the end of its travel, and (4) the apertures 32 and 34 provide an opening between the backs of the pistons 29 and 13 in the final position of the stroke of the piston 29, thus allowing the gas from the combustion chamber to act directly on the piston 13.

In the operation of the device, gas under pressure is applied through the opening 35 to the firing pin 22, shearing the pin 23, and firing the cartridge 28. The gas generated by the firing of the cartridge drives the floating piston 29 toward the bottom of the cylinder 11 rupturing the thin walled container and forcing the silicone oil through the passageways 33 and 34 into the cylinder 10. When the pressure in the cylinder 10 has attained a predetermined value, the pin 16 shears and piston 13 starts to move, the skirt 331 having now closed the opening to the passageway 33. This movement of the piston 13 is now cushioned and controlled by the oil which is enclosed in the restricted space between the rod 14 and the cylinder 10 and is discharged through the small opening 15 in the piston 13.

In the final position of the piston 29, the holes 32 open into the passageway 34, and permit the gas to act upon the piston 13, as disclosed and claimed in a copending application of Cecil C. Fawcett, Albert N. Stott and Creston F. Laager, Ser. No. 727,748, filed April 10, 1958, for Uniform Velocity Thruster.

We claim:

1. The combination of a first cylinder enclosing a piston perforated longitudinally and fixed to a rod extensible from said cylinder, a second cylinder having at one end a liquid retaining chamber and at the other end means for generating a gas pressure, means forming openings from said chamber to the front and rear of said perforated piston, and a floating piston interposed between said chamber and said pressure generating means and operable during the latter part of its travel to close the opening to the front of said perforated piston.

2. The combination of a first cylinder enclosing a piston perforated longitudinally and fixed to a rod extensible from said cylinder, a second cylinder having at one end a chamber enclosing an aluminum receptacle with a filler of silicone oil and at the other end means for generating a gas pressure, means forming openings from said chamber to the front and rear of said perforated piston, and a floating piston interposed between said chamber and said pressure generating means and operable during the latter part of its travel to close the opening to the front of said perforated piston.

References Cited in the file of this patent UNITED STATES PATENTS 

